The president’s frantic four days of hatchet-wielding at DHS and other agencies has blindsided senior Republicans, who are urging him to stop the bleeding. Republicans note that the president has the right to fire whomever he wants, Politico said, but few offered an explicit defense of his decisions to forceout DHS Secretary Kirstjen Nielsen; or remove the Secret Service director and threaten more terminations.

Cornyn said he has no idea what Miller’s “agenda” is in determining immigration policy because he isn’t Senate-confirmed and doesn’t correspond with the Hill.

Others believe the president is “losing it,” after backtracking on his threats to close the border, failing to get legal funding for the wall, and losing the court case on separation of families.

“Strikes me as just a frustration of not being able to solve a problem. Honestly, it wasn’t Secretary Nielsen’s fault. It wasn’t for lack of effort on her part. I don’t know if there’s anybody who’s going to be able to do more,” said Cornyn, who spoke to Nielsen on April 8 and planned to speak to her interim replacement, Kevin McAleenan, later in the day.

In an interview with Politico, Grassley expressed concern that Trump may soon boot U.S. Citizenship and Immigration Services Director Lee Francis Cissna and Kathy Nuebel Kovarik, who heads the office of policy and strategy at USCIS.

“I heard that they are on the list to be fired,” Grassley said. “They are doing in an intellectual-like way what the president wants to accomplish. So no, they should not go.”

On immigration, the G.O.P. has not been in lockstep with Trump. So even as the president pursues more aggressive strategies on the border, the party might not stick with him ahead of an election cycle that has the Senate up for grabs and with Republicans eager to take back the House.